Common Channel Signaling has been utilized advantageously by the Intelligent Network of the public switched telephone system to make available an expanding array of new subscriber service features. For example, U.S. Pat. No. 5,247,571 to Kay et al. discloses the use of Advanced Intelligent Network (AIN) implementation to provide area wide Centrex service. Each central office of a network of interconnected central offices is connected to a number of local telephone lines constituting a specified group. Call routing is carried out in accord with data stored in the AIN data base and with customer specified parameters, such as calling/called party number, time-of-day, day of the week, authorization codes, etc. After the central office switching system detects an off-hook, it determines whether or not the call originates from a line subscribing to the Area Wide Centrex (AWC) service. If not an AWC line, the system receives dialed digits and executes normal call processing routines. If the call is from an AWC line, the originating office receives dialed digits, suspends the call and sends a query message to the Integrated Service Control point (ISCP) through the Signaling Transfer Points (STP's). This query message, in Transaction Capabilities Applications Protocol (TCAP) format, identifies the calling station and the digits dialed as well as other pertinent information. Based on the identity of the business group as determined from the calling party's address, the ISCP retrieves from its data base a table of trunk group routing information. The ISCP formulates a response message, again in TCAP format, including the routing information, and transmits the response message back to the originating central office via the STP(s). The system then executes normal call processing routines for completing the call using the received routing information provided by the ISCP.
For the protection of customers against outgoing call fraud, various fraud prevention arrangements, including the use of screening filters, have been developed. Entry of a PIN number, password or other identifiers has been required to eliminate or reduce the ability to use a PBX, for example, as a gateway into the interexchange network by hackers or unauthorized callers.
One such protection system is described in U.S. Pat. No. 5,357,564 to Gupta et al., which discloses a virtual communications network (VCN) within a carrier's telecommunications network. Screening filters provided in the VCN data base control the admission of calls to the network. A screening filter generator is used to process historic customer specific traffic information, together with generic information relating to fraudulent call locations and VCN design parameters, in order to generate screening filters that are stored in a screening filter data base.
U.S. Pat. No. 4,935,956, to Hellwarth et al. discloses a system that operates without the intervention of a human operator and permits billing of long distance calls to called parties. The system includes microcomputers and operates with voice prompts to the calling and called party, one of several languages being selectable by the caller. System integrity and security is provided to prevent "hackers" and disgruntled personnel from committing fraud. The system includes a memory used for instant screening and evaluation of the acceptability of the specific number being called. An outgoing call blocking capability is included to prevent routing of unauthorized calls.
U.S. Pat. No. 5,276,444 to McNair exemplifies an access authorizing system having a shared centralized security control system that interfaces between a plurality of requesters and a plurality of destinations. The security system receives requests for access to the destinations and communicates to the destinations indications of a level of access that should be granted to each calling requester by that destination on a per request basis. The security system also authenticates the requester to a predetermined level from which the level of access that is to be granted is derived and causes a direct connection to be established between the requester and the destination. Once a connection is either made or denied between a requester and the corresponding requested destination, the security system is then free to process other requests from other requesters.
Notwithstanding the relatively sophisticated and flexible centralized network call control arrangements that have been in use and exemplified by some of the above noted patents, the need exists to effect from a central network location automatic restriction of the number of incoming calls that may be completed to individual subscribers. Such provision would be particularly desirable in a customer service in which collect calls are preauthorized. The ability to set in advance a maximum number of such calls placed to an individual subscriber for a given time period, while blocking calls in excess of the set number from completion, would be a means for preventing uncontrolled toll usage by the called subscriber, thereby fulfilling a need of the telephone company to reduce its exposure to subscribers with poor credit.
The called subscriber of an automated collect call service also has a need to set limits on the total number of calls for which he or she will be billed, as well as the number of calls received from individual callers. Conventional arrangements lack flexibility in blocking incoming calls to satisfy subscriber requirements. Such requirements may include restricting the time as well as the number of incoming calls to varying degrees for particular callers to the called subscribers, so that calls in excess of specifications will be blocked.
Called subscribers may require completion of a single call after blocking a specified number of calling attempts. For example, a subscriber may want to be connected only to the tenth caller. Conventionally, each time a non-busy call is made, the caller is denied completion until the tenth such call is received. With a high volume of calls, the completed call will not be the tenth call attempt, but instead the tenth non-busy call to get through. The successful caller thus in fact is not the tenth caller. The inconvenience in manually attending to these calls, the delay in receiving the non-busy attempts, and the inaccuracy in actually completing the call to the tenth caller, are inevitable consequences of the conventional approach.